Re: Gnome login performance

[Michael Meeks <michael ximian com>]

Hi Brian,

On Fri, 2002-10-04 at 16:06, Brian Cameron wrote:
> I did a performance analysis of how long it takes the various Gnome
> programs to startup on a Solaris system.

	Great work ...

> nautilus: 3.210 seconds user, 30.850 seconds system
> 
>    5.620 system seconds
>       gnome_vfs_module_callback_use_stack_info
>          g_hash_table_foreach
>             static function
>                g_strdup
>                   g_malloc

	So: ~20% of the time is spent doing this module_callback stuff.
Extremely odd - I've read the code, and it looks like it's used to allow
hooks for user authentication on a 'default' and 'per request' basis,
and custom hooks for various http states.

	As such - it seems a massively dis-proportionate cost to pay. Quite why
we go to all this effort to copy the default callbacks, and mess around
with per thread stack stuff is beyond me.

	It _looks_ to me as if:

	a) We should not copy the default authentication callbacks; if someone
is relying on the timing of exactly when they set the default callback
for a certain op [ NB. it can't be un-set etc. ], then they're smoking
crack and deserve oddness.

	b) We maintain a list of push/pop stack operations per thread [ so the
vfs can be used from multiple threads safely, for every op ]. That's
fine - we copy that off in gnome_vfs_module_callback_get_stack_info -
and add the default callbacks.

	  Then for reasons that are not clear - we copy the callback table from
this snapshot back into the per thread operation queue, which
(presumably) we just copied it from.

	  It's not clear to me what's going on there - someone needs to poke at
it.

	c) A push/pop system works nicely in combination with ref counting,
instead of doing all these deep copies of private callback data - we
should be (trivially) able to ref / unref them instead; resulting in a
nice (big) efficiency win.

	I hope someone is interesting in picking up some / all of that.

>    2.370 system seconds
>       nautilus_directory_get_internal
>          static function
>             gnome_vfs_uri_new_private
>                gnome-vfs_transform_get
>                   gnome_vfs_configuration_get_module_path
>                      stat64

	Where is nautilus_directory_get_internal called from ? and how many
times ? clearly doing stat floods is daft; but I never saw this in an
strace - which makes me curious.

	Regards,

		Michael.

-- 
 mmeeks gnu org  <><, Pseudo Engineer, itinerant idiot